1. Field of the Invention
The invention relates to methods of making monofilament yarns from thermoplastic resins.
2. Brief Description of the Prior Art
Prior to our invention, monofilament thermoplastic yarns useful, for example, in weaving and knitting fabrics were prepared by melt-spinning and solvent-spinning techniques; see for example U.S. Pat. Nos. 3,287,316 and 3,608,044. However, those skilled in the art appreciate that melt-spinning and solvent-spinning operations require substantial investment in capital machinery such as extruders, spinnerets and the like. In addition, many thermoplastic polymeric resins such as for example poly (ethylene oxide) are difficult and even impossible to spin into acceptable monofilament forms.
By the method of our invention, monofilaments of any thermoplastic polymeric resins may be readily and conveniently made from flat films of the resin. The apparatus required to carry out the method of the invention is relatively simple and inexpensive. The monofilaments prepared by the method of the invention are characterized in part by their advantageous, round cross-sectional configurations. The rounded monofilaments are usefully employed in weaving and knitting a wide variety of fabrics.
In certain embodiments of the invention, films of thermoplastic polymeric resins are drawn or molecularly oriented as a step in the method of the invention. Such orientations are generally well known in the prior art; see for example U.S. Pat. Nos. 3,400,193; 3,444,683; 3,448,187; and British Pat. No. 1,067,514.